Even though you need to ask a lot of questions to conduct an effective job interview, you cannot just ask anything.
Certain questions are legally forbidden, and asking them can lead to a discrimination lawsuit.

Asking questions without the intent of using the answer to discriminate against potential employees is no defense. Furthermore, even if someone volunteers information during the interview that could lead to discrimination, you can still be held liable. For that reason, never write down any information that falls into the categories of questions covered below or into any others you may believe could get you into legal trouble. In these circumstances, state that the volunteered information is not relevant to the interview and move on.

Luckily, you can easily avoid legal trouble by avoiding certain kinds of questions. Most of the forbidden questions are non-job related and you can keep yourself within legal bounds by sticking to professional topic in an interview.

Questions to steer clear of include:

How old are you?

People over 40 are protected by state and federal law to prevent age discrimination and therefore you may not inquire
about a candidate's age. Because most people graduate from high school at age 17 or 18, you may also not ask the year
someone graduated from high school.

However, you may ask about year of graduation from college because people attend college at different stages of life.

Are you married?

Leave this kind of question for getting acquainted after an offer has been extended.

Are you a citizen?

Although you will need to verify that someone is a citizen in order to hire them legally, you cannot find out by
asking this question.

You may ask it another way however: "Could you, after employment, submit verification of your legal right to work in
the United States?"

Are you planning on having children soon?

You may describe job requirements including travel, overtime and hours, and ask candidates if they have any
reason they cannot meet the requirements, but you may not ask about plans for childbearing.

May I have your maiden name?

Because knowing a maiden name may provide information about someone's national origin, it opens you up to
charges of discrimination. Likewise, you cannot ask for the name of a relative to contact in case of emergency.

You may ask for someone to contact as long as you do not stipulate that the person be a relative.

Are you disabled? Do you have any medical problems? Have you ever filed for worker's compensation?

The 1992 Americans with Disabilities Act (ADA) prohibits job discrimination based on disabilities of any kind.

The questions listed above are just a few examples. It is safest to assume that you cannot ask questions
about a person's health or physical capabilities. What you may do is describe job responsibilities and ask the
candidate if he/she is capable of performing the job functions "with or without accommodation?"